1. Field of the Invention
The present invention relates to a thiazolidine-4-one derivative or a non-toxic salt thereof, a method for preparing the same, and a pharmaceutical composition containing the same as an active ingredient.
2. Description of the Related Art
Most nonsteroidal antiinflammatory agents are responsible for blocking enzyme, cyclooxygenase (COX) or prostaglandin G/H synthase, to reduce inflammation, pain, or fever. In addition, they inhibit uterus contraction caused by hormones and also inhibit growth of several cancers. Cyclooxygenase-1 (COX-1) was first discovered in bovine. The COX-1 is constitutively expressed in a variety of cell types. Unlike the COX-1, cyclooxygenase-2 (COX-2) is a recently discovered isoform of cyclooxygenase that can be easily induced by mitogen, endotoxin, hormone, growth factor, or cytokine.
Prostaglandin is a potent mediator for various pathological and physiological processes. The COX-1 plays important physiological roles such as in the release of endogenous prostaglandin, the maintenance of the shape and the function of stomach, and the blood circulation in the kidney. On the other hand, the COX-2 is induced by an inflammatory factor, hormone, a growth factor, or cytokine. Therefore, the COX-2 is involved in pathological processes of prostaglandin, unlike the constitutive COX-1. In this regard, selective inhibitors of the COX-2 produce fewer and less side effects in terms of action mechanism in comparison with conventional nonsteroidal antiinflammatory agents. In addition, they reduce inflammation, pain, and fever and inhibit uterus contraction caused by hormones and growth of several cancers. In particular, they are effective in decreasing side effects such as stomach toxicity and kidney toxicity. Still furthermore, they inhibit the synthesis of contractile prostanoid, thereby leading to suppression of the contraction of smooth muscles. Therefore, they help in preventing premature birth, menstrual irregularity, asthma, and eosinophilic disease.
Recently, it was reported that nonsteroidal antiinflammatory agents are effective in treating large intestine cancer [European Journal of Cancer, Vol 37, p2302, 2001], prostate cancer [Urology, Vol 58, p127, 2001], and dementia [Exp. Opin. Invest. Drugs, Vol 9, p671, 2000].
In addition, it is anticipated that selective inhibitors of the COX-2 would be effective in treating osteoporosis and glaucoma. Utility of selective inhibitors of the COX-2 is well described in publications [John Vane, xe2x80x9cTowards a Better Aspirinxe2x80x9d in Nature, Vol.367, pp215-216, 1994; Bruno Battistini, Regina Botting and Y. S. Bakhle, xe2x80x9cCOX-1 and COX-2: Toward the Development of More Selective NSAIDsxe2x80x9d in Drug News and Perspectives, Vol.7, pp501-512, 1994; David B. Reitz and Karen Seibert, xe2x80x9cSelective Cyclooxygenase Inhibitorsxe2x80x9d in Annual Reports in Medicinal Chemistry, James A. Bristol, Editor, Vol. 30, pp179-188, 1995].
Various selective COX-2 inhibitors having different structures are known. Among them, a selective COX-2 inhibitor having a diaryl heterocyclic structure, i.e. a tricyclic structure has been widely studied as a potent candidate. The diaryl heterocyclic structure has a central ring and a sulfonamide or methylsulfone group attached to one of the aryl rings. An initial substance having such diaryl heterocyclic structure is Dup697 [Bioorganic and Medicinal Chemistry Letters, Vol 5, p2123, 1995]. Since then, SC-58635 having a pyrazol ring (Journal of Medicinal Chemistry, Vol 40, p1347, 1997) and MK-966 having a furanone ring (WO 95/00501) were discovered as derivatives of the Dup697.
One selective COX-2 inhibitor, Celecoxib of formula 4 is disclosed in U.S. Pat. No. 5,466,823. The Celecoxib is a substituted pyrazolyl benzenesulfonamide derivative. 
Another selective COX-2 inhibitor, Rofecoxib of formula 5 is disclosed in WO 95/00501. The Rofecoxib has a diaryl heterocyclic structure with a central furanone ring. 
Valdecoxib of formula 6 as another selective COX-2 inhibitor is disclosed in U.S. Pat. No. 5,633,272. The Valdecoxib has a phenylsulfonamide moiety with a central oxazol ring. 
The selective COX-2 inhibitors of formulas 4 to 6 are effective inflammatory therapeutic agents with fewer and less side effects in comparison with conventional nonsteroidal antiinflammatory agents.
An aspect of the present invention provides a thiazolidine-4-one derivative of formula 1 or a non-toxic salt thereof.
Another aspect of the present invention provides a method for preparing a thiazolidine-4-one derivative or a non-toxic salt thereof.
Another aspect of the present invention provides a pharmaceutical composition comprising a thiazolidine-4-one derivative or a non-toxic salt thereof as an active ingredient for the treatment of fever, pain, and inflammation.
Yet another aspect of the present invention provides a pharmaceutical composition comprising a thiazolidine-4-one derivative or a non-toxic salt thereof as an active ingredient for the treatment of cancers and dementia.
According to an aspect of the present invention, there is provided a thiazolidine-4-one derivative represented by formula 1: 
wherein:
R1 and R2 each independently represent hydrogen, C1-C3 alkyl, halogen, methyl substituted with halogen, C1-C3 alkoxy substituted with halogen, cyano, or nitro;
or a non-toxic salt thereof.
Preferably, the R1 and R2 are each independently selected from hydrogen, C1-C3 alkyl, halogen, or cyano.
Preferably, the position of R1 and R2 is respectively 3- and 4-, 2- and 4-, 3- and 5-, or 3- and 2-, and more preferably 3- and 5-, or 3- and 4-.
The thiazolidine-4-one derivative represented by formula 1 may be a pure optical isomer or a mixture of optical isomers.
The thiazolidine-4-one derivative of formula 1 may be present in a form of a non-toxic salt. The term, xe2x80x9cnon-toxic saltxe2x80x9d as used herein refers to a pharmaceutically acceptable, toxin-free salt, including an organic salt and an inorganic salt.
The Inorganic salt of the thiazolidine-4-one derivative of formula 1 includes an inorganic salt of aluminum, ammonium, calcium, copper, iron, lithium, magnesium, manganese, potassium, sodium, or zinc but is not limited thereto. Preferably, an inorganic salt of ammonium, calcium, potassium, or sodium is used.
The organic salt of the thiazolidine-4-one derivative of formula 1 includes an organic amine salt of primary, secondary, or tertiary amine, substituted amine that is present in nature, or cyclic amine, or a salt of a basic ion exchange resin but is not limited thereto. Examples of the salt of a basic ion exchange resin include, but are not limited to, a salt of arginine, betaine, caffeine, choline, N,N-dibenzylethylenediamine, diethylamine, 2-diethylaminoethanol, 2-dimethylaminoethanol, ethanolamine, ethylenediamine, N-ethylmorpholine, N-ethylpyperidine, N-methylglucamine, glucamine, glucosamine, histidine, hydroamine, N-(2-hydroxyethyl)pyperidine, N-(2-hydroxyethyl)pyrrolidine, isopropylamine, lysine, methylglucamine, morpholine, piperazine, pyperidine, polyamine resin, procaine, purine, theobromine, triethylamine, trimethylamine, tripropylamine, and tromethamine.
The thiazolidine-4-one derivative of formula 1 may be present in a form of an organic acid salt or an inorganic acid salt.
Examples of the organic acid salt or the inorganic acid salt of the thiazolidine-4-one derivative of formula 1 include, but are not limited to, a salt of acetic acid, adipic acid, aspartic acid, 1,5-naphthalene disulfonic acid, benzene sulfonic acid, benzoic acid, camphor sulfonic acid, citric acid, 1,2-ethane disulfonic acid, ethane sulfonic acid, ethylenediaminetetraacetic acid, fumaric acid, glucoheptonic acid, gluconic acid, glutamic acid, hydroiodic acid, hydrobromic acid, hydrochloric acid, icethionic acid, lactic acid, maleic acid, malic acid, madelic acid, methane sulfonic acid, mucinic acid, 2-naphthalenedisulfonic acid, nitric acid, oxalic acid, pentothenic acid, phosphoric acid, pivalric acid, propionic acid, salicylic acid, stearic acid, succinic acid, sulfuric acid, tartaric acid, p-toluene sulfonic acid, undecanoic acid, and 10-undecenoic acid. Preferably, a salt of succinic acid, hydrobromic acid, hydrochloric acid, maleic acid, methanesulfonic acid, phosphoric acid, sulfuric acid, or tartaric acid is used.
A preferred group of the thiazolidine-4-one derivative of the present invention is as follows:
3-(4-chlorophenyl)-2-(4-methanesulfonylphenyl)thiazolidine-4-one;
3-(3-fluoro-4-methylphenyl)-2-(4-methanesulfonylphenyl)thiazolidine-4-one;
3-(4-fluorophenyl)-2-(4-methanesulfonylphenyl)thiazolidine-4-one;
2-(4-methanesulfonylphenyl)-3-phenylthiazolidine-4-one;
3-(4-cyanophenyl)-2-(4-methanesulfonylphenyl)thiazolidine-4-one; or
3-(3,5-difluorophenyl)-2-(4-methanesulfonylphenyl)thiazolidine-4-one.
According to another aspect of the present invention, there is provided a method for preparing a thiazolidine-4-one derivative of formula 1 or a non-toxic salt thereof, comprising reacting 4-methanesulfonylbenzaldehyde of formula 2 with an aniline derivative of formula 3 in the presence of mercaptoacetic acid. 
wherein, R1 and R2 are as defined in formula 1.
Dehydration reaction of 4-methanesulfonylbenzaldehyde of formula 2 with an aniline derivative of formula 3 in the presence of mercaptoacetic acid can be performed in the same condition regardless of what the substitutes R1 and R2 are.
The aforementioned reactions are preferably carried out in a solvent which can be separated from water produced during the reaction by a Dean-Stark trap apparatus. Examples of the solvent include, but are not limited to, benzene, toluene, or xylene. Most preferably, toluene is used.
The reactions are preferably carried out by heating the reactant to the boiling point of the solvent and completing the reaction. It is most preferable that toluene is used as a solvent and the reactants are heated to the boiling point of the tolene and refluxed to complete the reaction.
The separation and purification of the reaction products can be performed by concentration or extraction, or other processes, which is conventionally used in organic synthesis process, and optionally by a silica gel column chromatography.
According to another aspect of the present invention, there is provided a pharmaceutical composition comprising a therapeutically effective amount of a thiazolidine-4-one derivative of formula 1 or a non-toxic salt thereof as an active ingredient and a pharmaceutically acceptable carrier for the treatment of fever, pain, and inflammation.
The pharmaceutical composition comprises a compound of formula 1 or a non-toxic salt thereof when it is a selective inhibitor of cyclooxygenase-2. Therefore, the pharmaceutical composition can be used as an antipyretic, an analgesic, and an antiinflammatory agent, with reduced side effects.
Conventional nonsteroidal antiinflammatory agents non-selectively inhibit the prostaglandin synthesis enzymes, cyclooxygenase-1 and cyclooxygenase-2. Therefore, various side effects may occur.
On the other hand, a compound of formula 1 and a non-toxic salt thereof selectively inhibit cyclooxygenase-2. Therefore, the side effects of conventional nonsteroidal antipyretics, analgesics, and antiinflammatory agents can be reduced.
The pharmaceutical composition of the present invention comprises a compound of formula 1 and/or a non-toxic salt thereof and a pharmaceutically acceptable carrier or excipient. Therefore, the pharmaceutical composition may be used as a substitute for conventional nonsteroidal antiinflammatory agents. In particular, due to the reduction of the side effects of conventional nonsteroidal antipyretics, analgesics, and antiinflammatory agents, the pharmaceutical composition of the present invention is useful for treating patients with peptic ulcer, gastritis, regional enteritis, ulcerative colitis, diverticullitis, gastrorrhagia, or hypoprothrombinemia.
The pharmaceutical composition of the present invention can be used in all inflammatory diseases associated with pathological prostaglandin and is particularly useful in treating osteoarthritis and rheumatoid arthritis which require high dosage of nonsteroidal antiinflammatory agents.
The pharmaceutical composition of the present invention can be administered in the form of an adult dosage of 50 mg/kg/day to 400 mg/kg/day of the compound of formula 1. An adequate dosage is determined depending on the degree of disease severity.
According to yet another aspect of the present invention, there is provided a pharmaceutical composition comprising a therapeutically effective amount of a thiazolidine-4-one derivative of formula 1 or a non-toxic salt thereof and a pharmaceutically acceptable carrier for the treatment of cancers and dementia.
Recently, it was reported that nonsteroidal antiinflammatory agents are effective for the treatment of large intestine cancer [European Journal of Cancer, Vol 37, p2302, 2001], prostate cancer [Urology, Vol 58, p127, 2001], and dementia [Exp. Opin. Invest. Drugs, Vol 9, p671, 2000]. Therefore, it is understood that the pharmaceutical composition of the present invention as a nonsteroidal antiinflammatory agent can also be used for the treatment of these diseases.
The pharmaceutical composition of the present invention can be administered in the form of an adult dosage of 50 mg/kg/day to 400 mg/kg/day of the compound of formula 1 or a non-toxic salt thereof. An adequate dosage is determined depending on the degree of disease severity.
The pharmaceutical composition of the present invention may be administered in the form of tablet, foam tablet, capsule, granule, powder, sustained-release tablet, sustained-release capsule (a single unit formulation or a multiple unit formulation), intravenous and intramuscular injectable solution, infusion solution, suspension, or suppository, or in other suitable dosage forms.
Sustained-release pharmaceutical dosage forms contain active ingredients with or without an initial loading dose. They are wholly or partially sustained-release pharmaceutical dosage forms to release active ingredients in a controlled manner.
Preferably, the pharmaceutical composition is orally administered.
The pharmaceutical composition further comprises a pharmaceutically acceptable excipient and/or diluent and/or adjuvant in pharmaceutically effective amounts.
Examples of the excipient and adjuvant include gellatin, a natural sugar such as sucrose and lactose, lecitin, pectin, starch such as corn starch and amylose, cyclodextrin and cyclodextrin derivative, dextran, polyvinylpyrrolidone, polyvinyl acetate, Arabic gum, arginic acid, xylose, talc, salicylic acid, calcium hydrogen phosphate, cellulose, cellulose derivative such as methylcellulose, methoxypropyl cellulose, hydroxypropylmethyl cellulose, and hydroxypropylmethylcellulose phthalate, fatty acid having 12 to 22 carbon atoms, emulsifying agent, oil and fat, in particular, vegetable glycerol ester and polyglycerol ester of saturated fatty acids, monohydric alcohol, polyhydric alcohol, polyglycol such as polyethylene glycol, aliphatic alcohol having 1 to 20 carbon atoms, or aliphatic saturated or unsaturated fatty acid ester having 2 to 22 carbon atoms with polyhydric alcohols such as glycol, glycerol, diethylene glycol, 1,2-propylene glycol, sorbitol, and mannitol.
Other suitable adjuvants include a disintegrating agent. Examples of the disintegrating agent include a cross-linked polyvinylpyrrolidone, sodium carboxymethyl starch, sodium carboxymethyl cellulose, and microcrystalline cellulose. A coating agent which is conventionally used in this field may also be used. Examples of the coating agent include acrylic acid and/or methacrylic acid and/or an ester polymer or copolymer thereof, zein, ethyl cellulose, ethyl cellulose succinate, and Shellac.
A plasticizer suitable for the coating agent is citric ester and tartaric ester, glycerol and glycerol ester, or polyethylene glycol with different chain lengths.
A liquid composition such as solution and suspension is formulated in water or a physiological acceptable organic solvent such as alcohol and aliphatic alcohol.
The liquid pharmaceutical composition may further comprise a preservative such as potassium solvate, methyl 4-hydroxybenzoate, and propyl 4-hydroxybenzoate, an antioxidant such as ascorbic acid, and a fragrant such as peppermint oil.
In addition, when the liquid pharmaceutical composition is formulated, a conventional solubilizer or emulsifier such as polyvinylpyrrolidone and polysolvate 80 may be used.
Other examples of suitable excipients and adjuvants are disclosed in Dr. H. P. Fielder, xe2x80x9cLexikon der Hilfsstoffe fur Pharmazie, Kosmetik und angrenzende Gebietexe2x80x9d [Encyclopaedia of auxiliaries for pharmacy, cosmetics and related fields].
Hereinafter, the present invention will be described more specifically by examples. However, the following examples are provided only for illustration and thus the present invention is not limited to or by them.